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Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 3. Jun 2019, 15:13
by Mats62
Hi. Looking at some older posts (I searched for hugemem) it seems that this question is a long-shot but I'll give it a try: Is there a way of using the GuestAdditions on a guest installed with CentOS 4.8?

Once I have the hugemem-kernel installed the guest won't work with the GuestAdditions installed, it seems to boo OK, mouse focus tries to shift to the VM but I am unable to really get to the screen of the VM. On my laptop, once this happens, the LED indicating caps-lock is flashing. In the office, two LEDs are flashing, the caps-lock and another one, can't remember which. That starts when the cursor floats over the VM window and stops as I move it away.

I realize this particular version of a VM has old GAs installed, that was intentional based on issues I had previously with newer GAs than that under CentOS 6.2. The behavior is the same also with current GAs. (I installed logs from the most recent boot)

As a sanity check, on my home PC I installed the 5.0.40 version completely and it looks the same.

Without the hugemem-kernel things look OK and without the GAs but with the hugemen-kernel, I also see no issues. Working without the GAs is very inconvenient though.

Any thoughts?
Thx + BR
Mats

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 3. Jun 2019, 16:32
by mpack
I assume "hugemem" just means a PAE based kernel.

Have you tried it? And did you enabled PAE support in the VM settings?
 Edit: [Later] Never mind - the log says that PAE is enabled and GAs 5.0.40 is running in the VM.

p.s. The VM only has 2GB RAM total. Why would you want to use PAE/hugemem? 

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 3. Jun 2019, 20:24
by Mats62
Hi mpack, hugemem is a requirement for the software we're running on these, no choice there I am afraid.

The 2G RAM is enough I think, I know of no performance issues. There's only 8G in the laptop and sometimes (but very rarely, granted) need more than one VM running at the same time.. I'll get more generous with RAM once I have 16G of it;-)
BR / Mats

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 4. Jun 2019, 10:15
by mpack
Mats62 wrote: The 2G RAM is enough I think, I know of no performance issues.
I wasn't thinking about performance issues, I was thinking that 2GB is completely addressable by a 32bit processor without tricks. I've never heard of software that requires the OS to support a particular memory model. Normally an app just request RAM in the size needed, it has no way to know what the RAM model is. And even if PAE mode eliminates limitation on contiguous allocations, 2GB is going to be less than that limit anyway. I noticed earlier that your host has 5GB free, so on this host you'd struggle to give any VM more RAM than a 32bit mode can handle.

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 4. Jun 2019, 11:28
by Mats62
Hi mpack. I don't know why our software is asking for the hugemem-kernel. The same software runs in simulated environments, as for example inside a VM, and on PCs controlling physical equipment. Such PCs used to be delivered with 8G of RAM at the time. There's a lot of inter-process communication using shared memory/semaphores and several different tools accessing/manipulating the same program objects. I think there are reasons behind the use of the hugemen-kernel.

My intention with the post was not to figure out if I need hugemem-kernel or not though, I do need to install that. I wanted to understand if I stand any chance whatsoever of using the GuestAdditions at the same time.

Any thoughts on that?
thx + BR / Mats

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 4. Jun 2019, 14:26
by mpack
How about if the VM is 64bit? Does the app refuse to run then too?
Mats62 wrote: My intention with the post was not to figure out if I need hugemem-kernel or not though, I do need to install that. I wanted to understand if I stand any chance whatsoever of using the GuestAdditions at the same time.
I addressed that in the first line of my first reply, albeit perhaps not explicitly enough: if my guess was correct that "hugemem" is just a marketing term for PAE support then AFAIK VirtualBox is perfectly happy with PAE being enabled: it provides an explicit option for it in the GUI after all. I have no idea what that caps lock flashing stuff is about: however 5.0.40 is really old, so I suggest you try it with current GAs.

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 4. Jun 2019, 18:45
by socratis
mpack wrote: I have no idea what that caps lock flashing stuff is about
That is code-word for kernel panics:
Flashing caps lock and scroll lock lights signal a kernel panic. This means that the Linux kernel has experienced an unrecoverable error and cannot continue, a condition equivalent to a Stop error ("BSOD" or "blue screen") on Windows.
...and many more in the query "linux caps lock flashes".

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 5. Jun 2019, 11:48
by Mats62
Hi socratis, thx. This suggests I will simply have to live without the GAs. Hi mpack, thx for your comments. Current GAs behave the same, I think I mentioned that, sorry if I didn't . Went back to 5.0.40 explicitly since they helped me fix graphics issues in CentOS 6.2 in the past, this was in 5.2.X I believe.

It appears that I break the kernel when installing the GAs.
We will look for a solution without using a VM so no need to invest more time on this.
Thx + BR
Mats

Re: Can't use GuestAdditions with hugemem-kernel, Old CentOS

Posted: 5. Jun 2019, 15:18
by mpack
Mats62 wrote:This suggests I will simply have to live without the GAs.
What about my suggestion to try a 64bit CentOS?

Hugemem/PAE should be irrelevant to a 64bit install. Software (even 32bit) should not insist on PAE when run in a 64bit environment, also 64bit removes any allocation size limits the software might be checking for... and the VirtualBox GAs definitely support 64bit Linux clients.